[Mike D]

There were a few examples of split plenums at oshkosh 2011. The most notable were on the piper sport from (I think) a company called renigade.
These are two separate plenums that cover the jugs only.
Are there any advantages to this setup? Disadvantages? Anyone tried this on an RV?

 

[DanH]

These are two separate plenums that cover the jugs only. Are there any advantages to this setup? Disadvantages? Anyone tried this on an RV?

Mike, I'm not aware of any data. My own reasoning says:

(1) the engine case is a hot body.....not like cylinder heads but hot none the less. Heat not removed from the case by by air contact must be removed by oil, which will require more air mass through the cooler as compared to a less heat-loaded oil system. Put another way, additional air mass through the cooler means additional cooling drag. Air contact with the case inside the upper plenum is free.

(2) separate plenums may be more difficult to seal.

 

[Alan Carroll]

Curious about this too. I believe I've seen photos of Reno formula racers that use these.

 

[Mike S]

Where you gonna get air for the oil cooler???

 

[Mike D]

The air for the oil cooler was coming from a separate NACA duct. It had it's own plenum.

The separate plenum was very well sealed and it seemed easy to do. It also had the air just dumping out into the cowling like a traditional baffle.

I did not put much thought into this setup at Oshkosh or I would have taken better notes and some pictures. But now I am thinking this could be a better way if you wanted to better control the routing of the air flow. I liked that the oil cooler was getting fresh cool air and I was thinking about using a door on the NACA duct to control the oil temps.

Does anyone have pictures?
The best I can find so far is this video taken at OSH,
http://http://www.youtube.com/watch?v=Gwso59sWhFc&feature=youtube_gdata_player
Check around 4:50 into the video.

 

[dpansier]

Example of a split plenum

 

[benbell4140]

That's an example of one helluva prop extension too

 

[LifeofReiley]

Been Done... N51PW RV6A

Look here...

http://websites.expercraft.com/n51pw/index.php?q=log_entry&log_id=4996

 

[jrs14855]

plenum

Its a bit easier to do the split plenum on the Continental as on the F1's because the pushrods are below the cylinders. I have seen the split plenum done on a Pitts with no problems with oil temp.

 

[RV8RIVETER]

Paul Lipps has seperate plenums on his IO-320 Lancair.

There are many Reno examples. The AR-6 reported cooling issues in the beginning, too much cooling. I am building seperate cooling plenums on mine.

To me the advantages are better control of air flow and does not allow air to flow in one inlet and out the other. I also am a believer in seperate oil cooler inlet, which I have as well.